This invention relates to improved multifilament polyester yarns for industrial uses. More particularly, it relates to a fiber finish composition specifically for polyethylene terephthalate yarns to be processed into tire cord for use as reinforcement in tires.
U.S. Pat. No. 3,687,721 to Dardoufas discloses an improved polyester tire yarn treated with a spin finish composition comprising hexadecyl stearate, glycerol monooleate, decaglycerol tetraoleate, ethoxylated tall oil fatty acid, sulfonated glycerol trioleate, and an ethoxylated alkylamine.
U.S. Pat. No. 3,730,892 to Marshall et al. discloses polyester tire yarn treated with an overfinish composition additionally comprising a silane having the structural formula ##STR2## wherein n=2 to 5. The composition is applied after the draw zone. The treated yarn can be subsequently processed into the cord with only a single dip treatment required to obtain the fiber to rubber adhesion necessary to use in tires.
While the polyester tire yarns disclosed above are successful commercial products, further improvements are desirable. When processed into tire cord and treated with resorcinol-formaldehyde-latex (RFL) dips, the tire cord may pick up too much of the RFL dip that subsequently flakes off the fiber in the treating oven, creating a housekeeping problem and a fire hazard. When the RFL treated tire cord is incorporated into the construction of a tire and the composite structure cured, it is essential to allow any entrained air in the composite tire to be transmitted out of a tire during curing. If, during dip treating, the tire cord picks up too much RFL dip that saturates the interstices of the tire cord, a pathway for entrained air may be blocked, thus increasing the probability of post-cure blows.